A strong stock as of late has been Charles River Laboratories (CRL) . Shares have been marching higher, with the stock up 11.3% over the past month. The stock hit a new 52-week high of $208.69 in the previous session. Charles River has gained 4.4% since the start of the year compared to the 5.4% gain for the Zacks Medical sector and the 10% return for the Zacks Medical Services industry.What's Driving the Outperformance?The stock has a great record of positive earnings surprises, having beaten the Zacks Con ...